Sulzer to supply hot and cold molten salt pumps for Chinese solar project

A major concentrated solar power (CSP) project in China has been selected by Sulzer, a global fluid engineering company, to supply hot and cold molten salt pumps for the plant.

The planned 100 MW solar project will use technology to provide electricity from the sun 24 hours a day.

Molten salts have been used in the nuclear industry for almost 70 years, and Sulzer has been involved in the design and manufacture of pumps that move high-temperature fluids around cooling circuits. The company was involved in pioneering the technology for use in the solar industry more than 15 years ago, enabling thermal energy to be stored overnight.

Molten salt is pumped into solar collectors (tower or parabolic mirror fields) where its temperature is increased from about 300°C to 600°C. The high temperature salt is then stored in a tank and sent to a heat exchanger where the heat energy is used to produce steam that will generate power using a turbine/generator. This circuit acts as a thermal battery that allows solar power plants to provide energy around the clock in good solar conditions.

Sulzer has experience in supplying hot and cold molten salt pumps to solar installations worldwide, including recent projects in China. The 100 MW CSP tower project is the first of its kind to use Sulzer pumps for both hot and cold circulation. Three cold molten salt pumps will be equipped with 2.6 MW motors and will extend 18 meters below the baseplate into the cold molten salt tank. They will be coupled to two hot pumps, and all pumps will be manufactured at Sulzer’s Suzhou facility in Jiangsu Province, China.

The biggest challenge with this project was the increased operating pressure required in the molten salt circuits. Smaller capacity facilities typically operate at around 50 bar, but this project required a supply pressure of 100 bar from the pumps.

Each pump is custom built and this design had to be designed to accommodate the increased pressure and slightly higher horsepower requirements. Compared to more common lower pressure pumps, there are a few key points, such as the design of the throttle sleeve and sleeve bearings, that need to be carefully assessed, properly designed and tested before the manufacturing process begins.

In this case, the end user wanted to achieve specific goals in the implementation of this project. They wanted international brands to provide key equipment that would ideally be manufactured in China and cost-effective compared to the competition.

Sulzer said the bare shaft pump will be engineered in Europe, with production being closely coordinated between facilities in Belgium and China. In addition, the company will offer a comprehensive support package for the products, which will be delivered through a local service center. By choosing Sulzer for both hot and cold pumps, the end user can also streamline their spare parts inventory.

As part of the agreement, local Sulzer engineers will be available to support the installation and commissioning of the equipment. Due to their length, the pumps will be assembled on site before installation in the storage tanks.

The installation follows several other successful projects implemented by Sulzer in China, including three hot pumps for another 100 MW CSP solar power plant, as well as six hot pumps and five cold pumps for a 42 MW parabolic trough plant.

—POWER This content was edited and provided by Sulzer AND DMA Europecompany marketing agency.